The present invention relates to a bicycle rear suspension system.
Mountain bikes are designed to be ridden over dirt trails. These dirt trails may have gravel, dirt, leaves, uneven terrain (e.g., boulders) and other elements which cause vibration and sudden jolts in the pedals, handlebar and seat of the bike. The vibration and jolts cause the bike rider to become fatigued at a faster rate compared to the fatigue rate if the rider had been riding over a smooth surface. For example, a mountain bike ridden over gravel causes vibration in the handlebar and seat. The rider must compensate for the vibration by absorbing the vibration with his/her arms and legs. As such, the rider must use additional energy to ride his/her bike over gravel. In another example, a mountain bike ridden over a mountain trail may have obstacles (e.g., boulders) that the rider must maneuver over or around. These obstacles or boulders may suddenly impact the bike's front and rear tires which are transferred to the bike's pedals, seat and handlebar. The rider must also absorb these impact forces with his/her legs and arms. Prolonged and repeated exposure to these sudden impact forces causes the rider to become fatigued at a faster rate compared to the fatigue rate if the rider had been riding over a smooth surface.
Modern mountain bikes are currently designed to reduce the amount of vibration and any impact forces transferred to the pedals, handlebar and seat. For example, mountain bikes may be installed with front shocks. The front shocks help to absorb any impact forces to the front tire and vibration caused by gravel, dirt, leaves, and obstacles on the bike trail. Similarly, mountain bikes may be fabricated with rear wheel suspension systems. These suspension systems help to absorb any vibration and sudden impact forces to the rear wheel caused by gravel, dirt, leaves, and obstacles on the bike trail. One typical rear wheel suspension system is a four bar linkage. The four bar linkage permits the rear wheel to rotate clockwise and counter clockwise about the front sprocket when the rear wheel rides over gravel, dirt, leaves, and obstacles along the bike trail. The four bar linkage is also connected to a shock absorber to absorb the impact forces caused by the terrain of the bike trail. In this way, the rear suspension system provides a smoother and more comfortable ride to the user.
Unfortunately, rear suspension systems such as the four bar linkage cause pedal setback when the rear wheel travels over the uneven terrain of the bike trail. The reason is that the rear wheel does not travel along a circular path about the front sprocket. Rather, the distance between the rear wheel (i.e., rear sprocket) and the front sprocket increases and decreases as the rear wheel is rotated about the front sprocket to absorb the impact forces caused by gravel, dirt, and obstacles along the bike trail. As such, the rider must compensate for the pedal setback causing the rider to become fatigued at a faster rate than if the rider was riding over a smooth surface. In sum, although rear suspension systems of bicycles help to reduce vibration and impact shocks by absorbing them into a shock absorber, rear suspension systems still have other inherent problems such as pedal setback.
Accordingly, there is a need in the art for an improved bicycle rear suspension that exhibits negligible or no pedal setback.